In large institutions such as hospitals and schools, the need for reducing water consumption is widely recognised as providing significant financial savings and environmental benefits. Furthermore, measures such as water metering have created a new demand for water saving measures in domestic applications.
According to the present invention, a water management system comprises a first water distribution system having a waste water outlet connected to an inlet of a settling chamber, the settling chamber having an overflow to a discharge chamber; and means associated with the lower part of the settling chamber for removing heavier than water contaminants therefrom; the discharge chamber having an outlet connected to a storage tank for supplying cleansed water from the first distribution system to a second water distribution system.
This waste water management system is capable of collecting and cleaning water from, for example, baths, handbasins and showers, and distributing the cleansed water to, for example, W.C.s and urinals. This provides a considerable reduction in overall water consumption.
The means associated with the lower part of the settling chamber for removing heavier than water contaminants may be a jet pump or an outlet duct communicating with the lower part of the settling chamber. However, a particularly effective means for removing the solid contaminants which allows the settling chamber to be automatically cleaned without any moving pump parts coming into contact with the contaminants and without interrupting the operating of the water management system is a fluidising unit comprising a supply duct which is arranged to be fed with water under pressure, and a discharge duct within the supply duct and projecting beyond the outlet of the supply duct for the discharge of a slurry of the solid contaminants from the settling chamber. The operation of the fluidising unit is improved when the water ejected from the supply duct is caused to swirl. The supply duct of the fluidising unit can be fed with a fresh supply of water from outside the water management system. However, it is convenient to feed the supply duct of the fluidising unit with water from the discharge chamber.
In order to facilitate start up of the fluidising unit, the discharge duct is preferably provided with an injector which is arranged to inject liquid to create a low-pressure region within the discharge duct. The injector is preferably fed by a bleed off line from the fluidising unit supply duct.
The water management system is preferably run by a common pump which is arranged both to pump water from the discharge chamber to the storage tank and to pump the water to the supply duct of the fluidising unit preferably at different times.
The cleansed water being supplied to the second water distribution system may still contain some contaminants, such as soap suds which are lighter than water. Therefore, some secondary separation and/or chemical treatment means may be provided for treating the water passing from the discharge chamber to the storage tank. The secondary separation means is preferably a hydrocyclone by means of which lighter than water contaminants are discharged from the water through the hydrocyclone overflow outlet. The hydrocyclone provides a compact secondary separator which can be simply driven by the (common) pump, the hydrocyclone underflow outlet preferably being connected to the storage tank.
The chemical treatment means may comprise means for adding chlorine, acid, alkali, scent or colour to the water. The various chemicals can be added to the water to make it more suitable for use in W.C.s and urinals. The water can be chlorinated so that it will not support bacteria thereby avoiding the need for further treatment of water in a W.C. or urinal such as by means of sanitised blocks. Alternatively the pH level of the water can be adjusted to assist in the subsequent treatment of sewage. A coloured die can be added to the water so that it is readily distinguishable from the potable water from the first water distribution system.
The settling and discharge chambers may be separate units connected by a pipe. However, to provide a more compact unit, the settling and discharge chambers are provided in a common tank, and separated by a weir which forms the overflow.
Further modifications to the water management system may include a rain water collection system having an outlet connected to the settling chamber, and/or a heat exchanger for recovering waste heat from water from the first distribution system. The former is particularly useful in, for example, factories and offices where the water in the first water distribution system is otherwise limited, while the latter is particularly useful in, for example, hospitals and hotels where a lot of hot water is used in the first water distribution system.
The waste water management systems described above can be supplied as a set of separate interconnectable components. This may be sufficient in larger buildings where space is readily available, for example alongside an air conditioning system or in a boiler room. However, for domestic applications a compact unit is desirable. In this case, the water management system may be supplied as a unitary tank being formed of a plastic material and being divided by partitions into compartments, a first compartment providing the settling chamber, a second compartment providing the discharge chamber, the weir being formed by a upper edge of one of the partitions separating the first and second compartments; a third compartment containing the hydrocyclone; and a fourth compartment providing a drain and having a contaminant outlet at its lower part, the discharge duct from the fluidising unit discharging into the drain compartment and the overflow outlet from the hydrocyclone discharging into the drain compartment; and the pump being mounted to the tank. Such a unit can be made sufficiently compact that it can be fitted under a kitchen sink.